Milk from domestic animals has been used as a source of protein and other products for the food and pharmaceutical industries for many years, and a variety of techniques are known for isolating these products. Milk is a colloidal suspension composed primarily of fats, lactose and proteins in water. Among ruminants and laboratory animals, milk contains an average of 30 to 140 grams of protein per liter, or about 4-17% by weight, depending on the species. The bulk of these proteins are caseins, which are complexed with calcium and phosphate in supramolecular structures known as micelles. The other major class of milk proteins is whey proteins, predominantly comprised of beta-lactoglobulin and alpha-lactalbumin, but also including lactoferrin, immunoglobulins, and serum albumin.
Milk proteins usually are isolated by a combination of processes including membrane filtration techniques as well as ion exchange adsorption procedures.
Lactoferrin is an 80 kD iron-binding glycoprotein found naturally in biological fluids such as saliva, bile, bronchial mucus, gastrointestinal fluids, cervico-vaginal mucus, seminal fluid, and milk. The richest source of lactoferrin is mammalian milk and colostrum. The concentration of lactoferrin in bovine skimmed milk is usually small, typically between 80-200 mg/ml depending on factors including the pasteurisation and other pre-treatment history of the skimmed milk. After precipitation of the casein present in milk, the concentration of lactoferrin in bovine whey is typically 10-100 mg/ml depending on the physical and chemical pre-treatment of the whey.
Lactoferrin has multiple postulated biological roles, including regulation of iron metabolism, immune function, and embryonic development. Lactoferrin has anti-microbial activity against a range of pathogens including Gram positive and Gram negative bacteria and fungi, including yeasts. The anti-microbial effect of lactoferrin is based on its capability of binding iron, which is essential for the growth of the pathogens. Lactoferrin also inhibits the replication of several viruses and increases the susceptibility of some bacteria to antibiotics and lysozyme by binding to the lipid A component of lipopolysaccharides on bacterial membranes.
It is an aim of a preferred embodiment of the present invention to provide an improved method for purifying lactoferrin from milk, particularly bovine milk, to improve purity.
All references, including any patents or patent applications, cited in this specification are hereby incorporated by reference. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents forms part of the common general knowledge in the art.